I have to say I am very happy with this update
Even though I have managed by just resending the books as it only takes a few seconds to actually upload, but this should make things even quicker now that I don't have to look and find the few books I have uploaded to the reader (they do not appear on top of the library list once uploaded) and then select them all again to be resent.
Not only have the Calibre team re added thumbnails but they have now fixed as best as they can the problem with the Sony Readers refreshing the thumbnails on first send!
Thanks so much for this support!